Maelstrom 21" With 4 - 2100 Gram 18" Passive Radiators

57873 Views 180 Replies 23 Participants Last post by Mike Cason, Jun 1, 2010

Mike Cason

Discussion Starter · Nov 21, 2009

Here is my build thread for the Maelstrom 21. I'll try to provide enough quality pics during my build for you.

I'm using Kevin's Maelstrom 21"er with the passive radiator design. I normally don't like building a passive radiator sub with a Qts over .4, but it is so close, I won't have a problem.

Here's the deal....23" x 23" x 60"; 13 cubes and 15.5 hz box tuning. With the typical passive radiator design there is more of a roll off but at this already low box tuning, I'll have more than plenty of bass. I needed the height to match my main speaker's height and get the cabinet volume I need. Better WAF here.

I just picked up the pallet of materials from my mill. My construction material is 1.25" mdf. It looked like I had ten bags of concrete in my truck going down the road. In the roll of plastic, I've got two sheets of Pionite black slate laminate to match all of my other speakers.

Cabinet resonance with this thick material; I don't think so. Moving it? Now that's another challenge.

Just got back from Houston with the materials so here is the first build pic:

Read more: So where are the Maelstrom-X 21" Build Threads! - Home Theater Systems - Electronics and Forum - HomeTheaterShack http://www.hometheatershack.com/for...elstrom-x-21-build-threads.html#ixzz0XWvNWnLo

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Mike Cason

Discussion Starter · #21 · Nov 24, 2009

Thank you for that Mike,

I always love those lower numbers.

I have a Houston buyer who may be buying my complete subs tomorrow night along with one or two of my amps, which will require me to buy new passives. I have to have a much bigger amp too. I can't hardly compress the driver by pushing down!

That leaves the door open for either John's 2100 gram 18's; or Kevin's passives. John's 18"ers have a much lower fs of 3.9 which is good. I've been building subs for years and have always used John's passives when they were available.

Here is the beast mounted temporarily and the cabinet sanded. I didn't realize the driver would be so large. That's a 23" wide cabinet!! :unbelievable: What a woofer!

A grill is going to be the biggest challenge to make and look nice.

Again, thank you for your time with the modeling! :clap:

Mike

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robseyes

· #22 · Nov 24, 2009

re: Maelstrom 21" With 4 - 2100 Gram 18" Passive Radiators

How bout a quad set of Kevin's 18's? Load em up full of mass (1500 to 1800 grams) and stand back! It'll take over 3000 watts before you run out of excursion on the pr's! Of course your room may be coming apart with over 122 db at 20hz anechoic. Those kind of lows can induce nausea!:hsd::unbelievable:

Kevin Haskins

· #23 · Nov 24, 2009

re: Maelstrom 21" With 4 - 2100 Gram 18" Passive Radiators

Mike Cason said:
Thank you for that Mike,

I always love those lower numbers. I was thinking the larger cabinet may be a benefit.

I have a Houston buyer who may be buying my complete subs tomorrow night along with one or two of my amps, which will require me to buy new passives. I have to have a much bigger amp too. I can't hardly compress the driver by pushing down!

That leaves the door open for either John's 15's or 18's; or Kevin's passives. John's have a much lower fs of 5 which is good. I may ask you to explore which one you would use, either three 15's or 2 to 3 18's. I wouldn't want you to spend any time on it until after I get cash in hand tomorrow night.

Here is the beast mounted temporarily and the cabinet sanded. I didn't realize the driver would be so large. That's a 23" wide cabinet!! :unbelievable: What a woofer!

A grill is going to be the biggest challenge to make and look nice.

Again, thank you for your time with the modeling! :clap:

Mike

It looks small in that picture.

Kevin Haskins
Exodus Audio

jreaves1637

· #24 · Nov 24, 2009

re: Maelstrom 21" With 4 - 2100 Gram 18" Passive Radiators

Great Build! With the box size stay the same if you went with 18" pr's instead of 15's and would that buy you anything? Would you be able to use few pr's if the 18's were used? I ask because I may want to build one myself.

Kevin Haskins

· #25 · Nov 24, 2009

re: Maelstrom 21" With 4 - 2100 Gram 18" Passive Radiators

jreaves1637 said:
Great Build! With the box size stay the same if you went with 18" pr's instead of 15's and would that buy you anything? Would you be able to use few pr's if the 18's were used? I ask because I may want to build one myself.

Sure.... you can build around 7 cubic feet with a single M-18 & a pair of PR-18s. It is still a house-wrecker.

Kevin Haskins
Exodus Audio

jreaves1637

· #26 · Nov 24, 2009

re: Maelstrom 21" With 4 - 2100 Gram 18" Passive Radiators

what I mean to say was how would the 21" do with 18" passive radiators? Didn't I see a thread somewhere about some 21" pr's?

Kevin Haskins

· #27 · Nov 24, 2009

re: Maelstrom 21" With 4 - 2100 Gram 18" Passive Radiators

jreaves1637 said:
what I mean to say was how would the 21" do with 18" passive radiators? Didn't I see a thread somewhere about some 21" pr's?

I have 21" PRs, which look identical to the M-21" but they are $150 each, $300/pr. Two is all you would need.

Kevin Haskins
Exodus Audio

Mike Cason

Discussion Starter · #28 · Nov 24, 2009

re: Maelstrom 21" With 4 - 2100 Gram 18" Passive Radiators

Kevin,

How would you hook up your Face amplifiers with the RCA LFE output on my Denon? How long have they been around and what is the RMA rate of these amps?

My cabinet is too narrow with inside 1.25" for your 21" passive radiators and grills.

Much appreciated.

Mike

Kevin Haskins said:
I have 21" PRs, which look identical to the M-21" but they are $150 each, $300/pr. Two is all you would need.

Kevin Haskins
Exodus Audio

Kevin Haskins

· #29 · Nov 25, 2009

re: Maelstrom 21" With 4 - 2100 Gram 18" Passive Radiators

Mike Cason said:
Kevin,

How would you hook up your Face amplifiers with the RCA LFE output on my Denon?

I wouldn't.... as much as your spending on a subwoofer, I'd get the SMS-1 so you have room measurement and EQ capability. There is no sense spending that much on a subwoofer and not having it.

Once you have that.... Denon RCA Output --------> XLR SMS-1 XLR --------> XLR Face Amp

How long have they been around and what is the RMA rate of these amps?

Mike

Good question.... I don't know. I've never had one of them returned outside of an audiophile that didn't like the fan noise. Face is relatively new, but well run and they stand behind the product better than most companies I've had to deal with. They are a good company, otherwise I wouldn't bother with them.

Kevin Haskins
Exodus Audio

Mike Cason

Discussion Starter · #30 · Nov 25, 2009

Re: Maelstrom 21"

Thanks for the info. I might budget that in a little later. I'm strapped. I found an XLR to RCA connector and have the great Reckhorn B-1 EQ which does well for me. Are the fans any noisier than QSCs or other similar amps?

I did manage to sell both of my subwoofers to a Shackster in Peoria Illinois and they are crated and ready to ship on Monday. I just need to strap them down. I'm glad I didn't part them out. They are too good to be wasted.

Thanks Kevin,

Mike

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Mike P.

· #31 · Nov 25, 2009

re: Maelstrom 21" With 4 - 2100 Gram 18" Passive Radiators

Since the 21" PR's won't work with your cabinet, there are a couple of 18" PR options from A.E. which I know you like.

Yellow is with four 18" 2100 PR's. Tuning frequency is 16.8 hz. 2000 watts input with a HPF at 15 hz.

Pink is with four 18" 1600 PR's. Tuning frequecy is 19.2 hz. 2000 watts input with a HPF at 15 hz.

PR excursion does not exceed 20 mm in both models. These are ballpark estimates as WinISD doesn't take into account power compression.

Text Line Slope Technology Font

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Mike Cason

Discussion Starter · #32 · Nov 25, 2009

You are right. AE's passives have the fs of 3.9 which is very low. I've been using his passives for many years and know his build quality. His 18s have a 3" peak to peak.

Thanks for the graph work. Very impressive work.

Kevin Haskins

· #33 · Nov 25, 2009

Re: Maelstrom 21"

Mike Cason said:
Thanks for the info. I might budget that in a little later. I'm strapped. I found an XLR to RCA connector and have the great Reckhorn B-1 EQ which does well for me. Are the fans any noisier than QSCs or other similar amps?

I did manage to sell both of my subwoofers to a Shackster in Perioria Illinois and they are crated and ready to ship on Monday. I just need to strap them down. I'm glad I didn't part them out. They are too good to be wasted.

Thanks Kevin,

Mike

I've not had a chance to hear every model by any stretch but most of the pro-sound amps I've been around, all have similar noise levels. I wouldn't count on it being any better or worse than another brand.

Kevin Haskins
Exodus Audio

Mike Cason

Discussion Starter · #34 · Nov 25, 2009

Re: Maelstrom 21"

I've been doing a lot of research on the Face products and they have been around for 10 years now. They aren't just a new kid on the block. You must have a great product to be in this business that long. I like the looks of the torrodial power transformer and the rest of their build. I'll let you know if I can afford one.

Thanks again Kevin...

btw....My avatar is now the Maelstrom 21" subwoofer!

Kevin Haskins

· #35 · Nov 25, 2009

Re: Maelstrom 21"

Mike Cason said:
I've been doing a lot of research on the Face products and they have been around for 10 years now. They aren't just a new kid on the block. You must have a great product to be in this business that long. I like the looks of the torrodial power transformer and the rest of their build. I'll let you know if I can afford one.

Thanks again Kevin...

btw....My avatar will be the Maelstrom 21" subwoofer instead of the one pictured on the left when I'm done.

Mike,

They are a good company, I like doing business with them and they have been excellent anytime I've needed them. They get top-marks from me.

Kevin Haskins
Exodus Audio

Mike Cason

Discussion Starter · #36 · Nov 28, 2009

2

Re: Maelstrom 21" Texas Monster

It's been far too long since I've posted some updated pics. Between finishing up getting the shipment of my other two subs ready for the trucking company, selling one of my amps, and working with my regular work, I've not had much time to work on the beast.

I've also purchased the Face F1200TS amp, XLR cable, I had the new 18" 2100 gram passive radiators built for me, and all the goodies are in transit.

I am finally breathing some life into it. Now it doesn't look too small. I need to work on internal bracing next and add a second layer of material behind the driver, probably 3/4 birch, screwed and glued. A 2 inch thick baffel should be stout enough. :unbelievable:

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Mike Cason

Discussion Starter · #37 · Nov 29, 2009

2

I decided against the second sheet of 3/4 plywood for the baffel. This mdf is 1.25" thick and that's a plenty!

These photos represent a much better design. My new special center braces couples the front and the rear of the cabinet as one unit and still leaves plenty of room for the drivers and cu. ft. I need. I added the 2 x 4 to stiffen up the sides.

Tomorrow, I'll build a 3/4 birch bottom so the mdf will have some protection from damages due to moving around and I'll make two 1 x 2 red oak runners for feet like I had on my last subs. It sure makes moving them in room much easier.

I'll put in some SonicBarrier on the bottom and top of the cabinet, install the rear panel of the cabinet, and start on the laminate. I'll add some polyfil after the driver is installed and before the passives go in.

I'm sure dreading the laminate work. I don't have any room for error on the size, only purchasing two sheets.

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robbo266317

· #38 · Nov 29, 2009

That's looking good, I can't wait to hear your impression of it.

Drizt

· #39 · Nov 29, 2009

WOW, you have done extremely well.

Those subs are going to have more head room than anyone would ever realistically use. And thats a great thing

Mike Cason

Discussion Starter · #40 · Nov 29, 2009

Thanks for the support! :T

I just ran the numbers again after completing the bracing, re-figuring the cabinet volume including the PR displacement and I'm still right on 13 cu.ft. 15 to 16 hz with room gain should make this a very acceptable build. :hsd:

I used to be so impatient with my projects when I got started years ago. I have learned to take my time and put in the extra labor to make my projects perform well and look nice which pays off in a big way.

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